The invention relates to a fluidized-bed heat exchange apparatus arranged, for example, to provide a heat exchange which can be regulated, with flexibility, for a flow of particulate material and powdery products which occurs during a heat treatment such as, the calcination of ores or the combustion of coal in a circulating bed.
It is desirable that a heat transfer, for example a heat recovery, is performed in a plant which is as compact as possible and which has as large a degree of operating flexibility as possible. These two conditions are not fulfilled in a satisfactory manner in the plants known hitherto. At present, conventional or multicellular fluidized beds are used, in which heat-exchange tubes are immersed. These apparatus are large in size and their thermal power varies only within a limited range, in stages and in a discontinuous manner. Mobile, aerated or non-aerated beds are also used, in which heat-exchange tubes are immersed. The operation of these beds cannot be easily controlled because of the poor distribution of the solids, and their efficiency is mediocre.
It is an object of the invention to provide a heat exchanger able to provide improved efficiency heat exchange between a charge of particulate material in the fluidized state and heat exchange tubes immersed in the fluidized bed.
The invention also seeks to enable the heat transfer between the powdery products and the heat-exchange tubes to be continuously regulated.